Gyroscopic compass



Nov. 24, 1942.

E. P. ROSS. j

GYROSCOPIC COMPASS Filed. Aug. 15, 1940 3 Sheets-Sheet '1 EuwtmmssATTORNEY Nov. 24, 1942., E. P. ROSS I GYROSCOPIC COMPASS Filed Aug. 15,1940 3 Sheets-Sheet 2 ig? i i 3s 38 R 5 A coMPAss LAYTTUDE,

INVENTOR Eiliaiil'; Ra s ATTOR Nmn 241, 1942. 5 055 I 2,302,894

. GYROSCOPIC COMPASS- Filed Aug. 15, 1940 3 Sheets-Sheet 5 INVENTORElLiottRRoss A TTORNE Y Patented Nov. 24, 1942 GYROSCOPIC COMPASSElliott P. Ross, Forest Hills, N. Y., assignor to Ford InstrumentCompany, Inc., Long Island City, N. Y., a corporation of New YorkApplication August 13, 1940, Serial No. 352,391 6 Claims. (01. 33-226)This application is a continuation in part of an application entitledGyroscopic compass, filed by me on January 11, 1939, Serial No. 250,287.

The invention herein disclosed relates to gyroscopic compassesand moreparticularly to a compass of this type wherein the customary pendulousgravity control is replaced by a suittion, that it will retain thisdirection in space regardless of its. position on the earth. Under theseconditions the spin axis of the compass gyroscope will point to thepole'of the heavens. and indicate not only the true north but thelatitude of the place. If these conditions could be fulfilled, such agyroscope would be the ideal compass.

The present-gyroscopic compasses however are maintained with the axis oftheir gyroscopes tangent to the earth's surface by the use of gravitypendulous devices. These compasses when on the equator are not disturbedby the rotation of the earth when they are on the meridian, since thespin axes of their gyroscopes are then parallel to the axis of theearth. However, as these compasses are moved to a position north orsouth of the equator, their gyro axes are no longer parallel to theearth's axis and the rotation of the earth causes them to depart fromthe meridian. Consequently various forms of compensating devices arenecessary to correct for the error commonly known as the latitude error.The angular movement of the axes of these compasses to maintain themhorizontal as they are moved in a north-south direction causes a furthertendency to depart from the meridian generally known as the north-southsteaming error.

' The pendulums used to maintain the gyro axis horizontal introduceadditional errors since they are disturbed by acceleration forces due toroll and pitch, and changes of speed and course of the ship. Inaccordance with one of the fundamental principles of the gyroscopiccompass the north end of the gyro axle tends to fall due to the rotationof the earth, when it is west of the meridian and rise when it is eastof the meridian. The use of this phenomenon to bringthe gyro axis to themeridian is well known and is most pronounced when the compass is at theequator. It is an object of the present invention to provide agyroscopic compass which will rapidly seek the meridian and when on themeridian is not subject to disturbing forces such as are produced inpendulous gyroscopic compasses by acceleration forces due toroll andpitch of the ship.

It is another object of the invention to provide a gyroscopic compassmounted on rectangular axes which are stabilized horizontally andvertically with reference to the surface of the earth.

It is another object of the invention to provide a gyroscopic compassmounted for three degrees of freedom onrectangular axes which arestabilized horizontally and vertically with respect to the surface ofthe earth and to apply to the axes torques in proportion to thelatitude, and course and speed of the ship.

In accordance with the invention these ob- Jects and certain advantageswhich will hereinafter appear are accomplished by taking advantage ofthephenomenon described above. The disturbing forces on the gyroscopiccompass due to roll and pitch are eliminated by the use of a gyroscopicstabilized base or frame. It is desirable that this base be of the typecontrolled by a pendulum to determine the vertical and com-' trated inthe drawings, and will be hereinafter pointed out in the claims.

In'the accompanying drawings: V

Fig. 1 is an isometric view illustrated somewhat diagrammatically of agyroscopic compass and mechanism embodying the invention;

Fig.- 2 is a sectional view taken along the line 2-4 of Fig. 1;

Fig. 3 is a sectional view partly broken away taken along the line 33 ofFig. 1;

Fig. 4 is a schematic diagram of a mechanism for computing correctionalprecessing forces to be applied to the compass gyroscope;

' Fig. 5' is an enlarged side view partly broken away, showing anotherform of spring connection; and

Fig. 6 is a wiring diagram showing the operation of the follow-upsystems in Fig. 1.

The mechanism illustrated in Fig. '1 consists of a gyroscopic compass Aand a gyroscopic stabilized base or support B.

The base B consists of a pair of-standards la and lb which arepermanently secured to the deck of the ship upon which the mechanism ismounted. The construction illustrated in Fig. 1 the standards la and lbform bearings for trunnions 2a and 2b that extend from a gyroscope frame2'. The standards la and lb are so posiling 34.

tioned that the axes of the trunnions 2s and 2b of the frame areparallel to the fore and aft line of th ship. Within the frame 2 thereis mounted a ring 3. The ring 3 has trunnions 3a and 3b that arejournaled in the frame 2, the axes of these trunnions being athwartshipor at an angle of 90 to the trunnion axis of the frame 2. Integral withopposite points of the lower edge of the ring 3 are downwardly extendingarms 30 and 3d from the lower ends of which are suspended. a gimbal ring4 which carries a gyroscope 5. The ring 4 has trunnions 4a and 41) thatare journaled near the ends of the arms 30 and 3d respectively, and thegyroscope 5 is mounted for oscillatory movement about the trunnions 5aand 5b jour-- naled in the gimbal ring 4. Integral with the upper edgeof the ring 3 and disposed at an angle of 90 from the arms so and 3d,are upwardly extending arms 3e and 3) which are joined together at theirupper and approximately mid-section points by integral portions 6 and I,respectively, to form a frame 8.

The gyroscopic compass A consists of a vertical gimbal ring 9, avertical or driven ring ID, a gyroscope H mounted for oscillatorymovement within the ring 9, and a compass card I 2. As shown moreclearly in Fig. 2, the compass card I2 has a hollow integral hub l3which fits over one end of a rod I4 and to which it is secured by meansof a pin l5. This rod is journaled for rotatable movement with thecompass card in a boss I8 on the part 6 of the frame 8 and another bossI! on top of the ring 9. The other end of this rod is secured to thedriven ring ill by means of a pin I8. The lubbers point, or the pointindicating the ship's head, is represented by the upper end IQ of a rod20 secured to the frame 3.

The vertical gimbal ring 9 is rotatably mounted for movement about avertical axis .A'A', the

upper end for movement about the rod l4 by means of the journal in theboss i7, and the lower end by means of a trunnionZl journaled in a boss24 on the part 1 of the frame 8. The trunnion rod 22 rotates in thetrunnion 2| and is secured to the driven ring IE! by pin 23. The drivenring Ill, as already mentioned, is secured at its upper end to the rodI4 for movement about the vertical axis with the compass card. Thegyroscope H is rotatably mounted within the gimbal ring 9 for movementabout trunnions Ila and I lb 1 which are journaled in the gimbal ring 9.Hubs He and I Id of the gyroscope l I, as shown in Fig.

- 1, have theiraxes in the north-south plane.

In order to take advantage of the fundamental principle of thegyroscope, that the north end of the axle of the gyroscope tends to falldue to the rotation of the earth when west of the meridian and rise whenit is east ofthe meridian, an inwardly extending eye 25 is provided onthe horizontal centerline of the driven ring ill. The hub lie at thenorth end of the gyroscope .II is connected by means of a spring I le to.the eye 23.

Precessing forces for causing the spin axis of the gyroscope i I toremain in the meridian plane as the earth rotates and to remainhorizontal as the compass is carried in a north-south direction bymovement of the ship are applied by the torque motors 26 and 21respectively, under the control of transmitters 28 and 29 whichrepresent the outputs of the computing mechanism 30 shown in Fig. 4, aswill be described later. The stator 3| of the motor 26 is secured to thegimbal'ring 9 by brackets 32 and the shaft 33 of the rotor is rotatablysecured to the trunnion Ha by the coup- The stator 35 of the motor 21 issecured to the trunnion rod 22 by the coupling 38. It is to beunderstood that suitable slip rings or flexible leads will be providedfor the electrical connections to the torque motors.

In order to maintain the plane of the driven ring H] in fixedrelationship to the gimbal ring 9 of the gyroscope H, and consequently,to transmit the true north heading of the gyroscope to the compass cardl2, use is made of a follow-up motor 40 controlled by means ofelectrical contacts 39. The follow-up motor 40 is mounted on and securedto the part 8 of the frame 8 by means of a bracket 4|. The contacts 39,see Fig. 6, include a pair of spaced electrically insulated contacts 39aand 39b that are mounted on a bracket 42, secured to the ring ID, bymeans of an arm 43, and a roller contact 44v that is mounted on abracket 45 integral with the gimbal ring 9 of the gyroscope H. Asrelative movement between the gimbal ring 9 and the ring ID occurs aboutthe axis A'-A, the contact 44 rides off thecentral insulated sectionbetween the contacts 39:! and 39b and on to one or the other of thecontacts. Such contact between the contacts 44 and 39a or 39b causes theoperation of the motor 40,

by electrical connections, hereinafter to be described and shown in Fig.6, to drive the ring III in a direction to restore the proper angularrelationship between the gimbal ring 9 and the driven ring Hi. This iseffected by means of a pinion 48 secured to one end of a shaft 41 anddriven by the motor 40. The pinion 46 meshes with gear teeth 48 on'theperiphery of the compass card I2. Since the compass card is connected tothe driven ring N) by means of the rod l4, movement of the motor 40 iscommunicated to the ring II. The other end 49 ofthe motor shaft 41 isconnected to a transmitter 50 mounted on a bracket 5| The transmitter 50transmits the heading of the ship to the customary repeater motorslocated about the ship and to a repeater motor 52 er contact 44 isconnected by means of a wire 5] to the other line wire 58.

Since the construction of the stabilized base B is well known in the artand may be of the type described and shown in the above mentionedpatent, only such parts have been illustrated in the drawings that arepertinent to this invention. The description therefore of the base Bwill be limited to the manner in which it cooperates as a whole in thecombination. in which it occurs with the other elements in thisinvention. Referring again to Fig. 1 the operating mechanism of the basewill now be briefly described.

The stabilized base B is utilized to maintain the frame 8 andconsequently the gyro'scopic compass A within which frame it is mounted,continuously in the vertical, that is, the axis A'--A' is continuouslymaintained vertical. Due to the use of a stabilized base from which toap ply the precessional corrections to the compass gyroscope, no effectfrom accelerations due to roll and pitch or change of ships speed andcourse is communicated to the compass gyroscope.

Due to the pendulous controls, not shown, the axis of the gyroscope ismaintained continuously vertical. These pendulous controls arepreferably compensated for the forces due to accelerations such as areproduced by change of course and speed of the ship as described andillustrated in the above mentioned patent. As the ship rolls andpitches, motor operated followup mechanisms cooperate to maintain thering 3 continuously horizontal and the axis A'--A parallel to the axisof the gyroscope 5 in the.

following manner.

Movement of the gyroscope 5 about the axes 5a and 5b relative to thegimbal ring 4 controls the movement of the frame 2 about the trunnions2a and 2b. This movement of the frame 2- is effected through a follow-upmotor 58 and elec-v trical contacts 88.. The follow-up motor 88 is-connected to. the frame 2 through a worm 8| mounted upon a shaft 62 ofthe motor 58 and a segmental worm gear 83 integral with the frametrunnion axis of the frame 2. The contacts 88 include apair of spaced,electrically insulated contacts 880 and 88b (Fig. 6) that are mounted ona bracket 64 secured to the gimbal ring 4, and

a roller contact 88c that is mounted on a bracket 65 secured to thecasing of the gyroscope 5 To effect the operation of the motor 88 a wire88 connects one side of the motor to a line wire 84. The contacts 88a.and 88b are separately connected to the motor through wires 81 and 88respectively and the roller contact 880 is connected by means of a wire88 to a line wire 58. Mounted on the shaft 82 between the motor 58 andthe worm BI is a gear 18 which meshes with a gear 1| mounted on a shaft12 of a transmitter 13. It will be understood that the motor 58, worm 8|and transmitter'13 with the connecting shaft and gearing are suitablymounted on the standard Ia by mountings not shown.

As relative movement between the gyroscope I and the gimbal ring 4occurs about the trunnions 2. The worm gear 68 is concentric with the isand 5b; the contact 880 rides of! of the central insulated sectionbetween the contacts 88a and 88b and on to one or the other of thecontacts.

. Such contact between the contact 880 and the ,relative to the ring 3controls the movement of the ring 3 about the trunnions 3a and 3b. Thismovement of the ring 3 is effectedthrough a follow-up motor 14 andelectrical contacts 15. The follow-up motor 14 is connected to drive thering 3 as follows: a gear 18 mounted on the shaft 11 of the motor mesheswith a gear 18 connected to one side of a compensating differential 18;the other side of the differential is connected to a gear- 88 freelymounted on shaft 8| and meshing with a gear 82 secured to one end of ashaft 83; on the other end of the shaft 83 is secured a bevel pinion 84which meshes with the arcuate rack 85 mounted on the arm 8c of the frame8; the shaft 8| is secured at one end to the spider 86 of thedifferential 18 by a pin 18a and at the other end carries a gear 81; thegear .81 meshes vertical,

with a gear 88 integral with the trunnion 2b of the frame 2; thetrunnion 2b is journaled to receive the shaft 83 freely rotatabletherein. It will be seen that as the frame 2 rotates relative to thestandard ID, the gear 84 will be rotated therewith, through thecompensating differential 18, by means of the gears 88 and 81, the shaft8|, spider 86, gears 88, 82 and the'shaft 88. Mounted on the shaft 11between the motor I4 and the gear 18 is a gear 89 which meshes with agear 88 mounted on the shaft 8| of a transmitter 82. It will beunderstood that the motor 14, transmitter 82, differential 18,associated shafts and gearing are suitably mounted on the standard lb bymountings not shown. The electrical contacts 15 include a roller 18a(Fig. 6) that is mounted on the bracket 84 which is secured to thegimbal ring 4 and two spaced electrically insulated contacts 15b and 150that are mounted on a bracket 88 secured to the arm 8d near its lowerend. To effect the operation of the motor 14, the contacts 15b and 150are connected to the motor by wires 84 and 85 respectively.

, other line wire 58 is connectedv by a conductor tween the gimbal ring4 and the ring 8 is main- I tained.

From the foregoing it will be seen that the ring 8 corresponds at alltimes with the gyroscope 8. Since the spin axis of the gyroscope isvertical the ring8 will be horizontal and represent a true horizontalplane. Consequently, the axis A'--A of the gyroscope A, is maintainedcontinuously The transmitter 18 transmits the motion due to the roll ofthe ship and the transmitter 82 transmits the motion due to the pitch ofthe (ship, and these motions may be combined togather to maintainanother object remotely aitu ated in a true horizontal plane. I I Itwill be apparent that instead of a composite unit as shown, the compassA-may be separated from the stabilized mount B to form separate unitswith appropriate connections to maintain the axis A'-A' vertical, thatis, parallel to the axis of the gyroscope 5. 1

In Fig. 5 is shown a preferred form of spring connectionbetween thegyroscope II and the driven ring I8. Upper and lower spaced spring leafmembers, in pairs, 88, 88 and I88, .I8I are secured by screws I82 to abracket I83 integral with the driven ring I8 at'its horizontal centerline. The outer member of each pair of these springs, or the members 88and IN, are made of heavier material than that of the inner members 88and I88. The outer spring members are separated from the inner membersby distance pieces I84 and I88. A lug I88 integral with a bracket I88ais secured by screws I81 and I8lto the hub No of the gyroscope II. Thelug I88 is operatively associated with the spring members and thesemembers resist any tendency of the lug I88 to change its positionrelative to the horizontal.

In accordance with one of the fundamental principles of the gyroscopiccompass already described, that the north end of the axis of thegyroscope tends to fall due to the rotation of the earth when west ofthe meridian and rise when it is east of the meridian; if the axis ofthe gyroscope departs from the meridian toward the east thus causing thehub I Ic to rise; the lug I06 will contact one of the upper pair ofspring members; the reaction of the spring will cause the gyroscope IIto precess in a direction which will return the axis to the meridian.Similarly, departures west of the meridian will cause the hub I la tofall, so that the lug I06 will contact one of the lower spring members.The reaction of this spring will cause the gyroscope to precess in adirection which will return the axis to the meridian. Any tendency forsmall departures from the meridian on the part of the axis will beresisted by the smaller spring members 99 and I00. Larger departuresfrom the meridian, however, such as would occur in starting up thecompass,

will cause the heavier springs 98 and IOI to come into action, whereuponthe reaction thereof will cause the compass to rapidly precess to themeridi'an,

It will be seen that the operation of the spring II e of Fig. 1 will beeffective in asimilar manner to cause the axis of the gyroscope torapidly seek the meridian on departure therefrom. The follow-up contacts39a and 392) are so connected and arranged that the follow-up motor 40maintains the rings 9 and I0 in a relatively fixed relationship, and thedeparture from this relationship is never suflicient to permit anyappreciable torque to be produced about the vertical axis A-A by thespring IIe. Consequently the only eifective torque applied to thegyroscope by the spring I Ie is about the horizontal axis Ila-IIb, thesame as the torque applied by the leaf spring members of Fig. 5.

As pointed out in the patent of Hannibal C. Ford, Number 1,628,136, aprecessing torque may be applied to the compass gyroscope about itsvertical mounting axis to cause it to precess about Its horizontal oreasbwest trunnion axis so that the spin axis remains horizontal as thecraft on which it is mounted changes latitude. Likewise torques may beapplied about the east-west trunnion axis to cause the gyroscope toprecess about its vertical mounting axis so that its spin axis remainsin the meridian plane regardless of the rotation of the earth oreast-west movement of the craft on which it is mounted. By continuouslyapplying such torques, the spin axis of the gyroscope will remain in themeridian plane except for wandering due to friction or variations in theprecessing torques. These wanderings are corrected by the springconnection to the stabilized base as shown at He in Fig. 1 or in apreferred form in Fig. 5.

The value of the correction torques to be applied to the compassgyroscope may be deter mined as shown in Patent No. 1,628,136 abovereferred to or by other means, one of which is shown in Fig. 4. It isevident that the torque necessary to cause the spin axis of thegyroscope to remain horizontal is that torque which will precess thegyroscope at the angular rate of north-south movement of the craftrelative to the earth and is proportional to So.cos C0 where S0 is thespeed of the craft and Co is the course or direction of movement of thecraft relative to the meridian plane. The torque required to precess thegyroscope to stay on the meridian as the earth rotates and the craftmoves in an eastwest direction is proportional to locate a pin I31.

sin L+So-sin Co-tan L where L equals the latitude. Appropriate constantswill be included in each equation to allow for the characteristics ofthe particular gyroscope to which they are applied.

Referring now to Fig. 4, as already pointed out, the receiver motor 52is actuated in accordance with the heading of the ship Co. The anglethus received is introduced in a component solver I03 by a servomotorIIO controlled by follow-up contacts III which are associated with thereceiver motor 52 in the well known manner. The servomotor 'IIO rotatesa vector gear II2 by a shaft H3 and associated gearing. The ship speed(So) is introduced by a handcrank H4, and a customary compensatingdifierential Hi, to a gear IIB which carries a spiral cam to control thelength of the vector. The direction and length of the vectorrepresenting ships motion is represented by a pin II! which locatescomponent slides H8 and 'I I9 in accordance with the sine and cosine ofthe ships movement. The slide II9 drives the transmitter 29 to transmitvalues proportional to So.cos Co to the torque motor 21. The slide II8through shaiting I20 locates an input slide I2I, of a compoundmultiplying and dividing mechanism I22, in accordance with S0 sin Co.

A component solver I23 is set for latitude of the craft by a handcrankI24 which rotates a gear I25 carrying a; pin I26 which locates twocomponent slides I21 and I28 in accordance with the sine and cosine orthe latitude. The sine slide I21 carries an arm I29 which acts as asecond input to the mechanism I22. An arm I30 pivoted at a point I3I islocated angularly by the input slide I2I and a pin I32 located by theintersection 01' the arm I29 and the arm I30 determines the position ofthe cross slide I33 in accordance with So.sin Co.sin L. The cross slideI33 carries an arm I34 which cooperates with a slide I35 located inaccordance with cos L by the slide I28 and connecting shafting I36 toThis pin in turn locates an output arm I38 and slide I39 in accordancewith Sosin Co.sin L cos L are of a type in which the torque isproportional, to the displacement of the controlling transmitter.

Dials I 44 and I45 are actuated by the hand cranks H4 and I24 toindicate the values of ships speed and latitude respectively. It isevident that these values may be introduced automatically by suitableconnections to the ships log and dead reckoning mechanism.

It will be obvious that various changes may be'made by those skilled inthe art in the details of the embodiment of the invention disclosed inthe drawings and described above within the principle and scope of theinvention as expressed in the appended claims.

I claim:

; 1. In a gyroscopic compass on a moving craft, the combination of astabilizing gyro-vertical adapted to maintain a horizontal plane, auniversally mounted frame, power-driven follow-up means controlled bysaid gyro-vertical for driving said frame in accordance with theposition of the gyro-vertical to maintain said frame horizontal, acompass gyroscope having horizontal and vertical supporting axes mountedin the frame, means for applying a torque to the gyroscope about itsvertical supporting axis proportional to functions of the course andspeed of the craft,-a ring mounted in said frame adapted to angularmovement about a vertical axis, means to move said ring about itsvertical axis in accordance with the movement of the gyroscope about itsvertical axis, and precession-inducing, means connected to the ring andto the gyroscope adapted to restore the spin axis of said gyroscope tothe meridian plane upon angular movement of the gyroscope relative totheframe,

due to the departure of the spin axis of said gyroscope from themeridian plane.

2. In a gyroscopic compass on a moving craft, the combination of astabilizing gyro-vertical adapted to maintain a horizontal plane, auni.- versally mounted frame, power-driven follow-up 1 means controlledby said gyro-vertical for driving said frame in accordance with theposition.

of the gyro-vertical to maintainsaid frame horizontal, a compassgyroscope having horizontal and vertical supporting axes mounted in the.frame, means for applying a-torque to the gyroscope about its horizontalsupporting axis proframe adapted to angular movement about a verticalaxis, means to move said ring about its vertical axis in accordance withthe. movement of the gyroscope about its vertica l'axis, andprecession-inducing. means connected tothe ring and to the gyroscopeadapted to restore the spin axis of said gyroscope to the meridian planeupon angular movement ofthe gyroscope relative to the frame, due to thedeparture of the spin axis of said gyroscope from the meridian plane.

3. In a gyroscopic compass for use on a moving craft, the combination ofa stabilizing gyrovertical adapted to maintain a horizontal plane, auniversally'mounted frame, power-driven follow-up means controlled bysaid gyro-vertical for driving said frame in accordance with theposition of the gyro-vertical to maintain said framehorizontal, acompass gyroscope pivoted on supporting axes for three degrees offreedomin said frame, means for applying torques to the gyroscope about itsvertical supporting axis proportional to functions of the course andspeed of the craft and about the horizontal supporting axis proportionalto functions of the course, speed and latitude of the craft, a ringmounted in said frame adapted to angular movement about a vertical axis,means for moving said ring about its vertical axis in accordance withthe angular movement of the gyroscope about its vertical axis, andprecession-inducing means connected to the ring and to the gyroscopeadapted to restore the spinaxis of said gyroscope to the meridianplaneupon angular movement of the gyroscope relative to the frame, dueto the departure of the spin axis of said gyroscope from the meridianplane.

4. In a mechanism of the type described for adjusting the spin axis of acompass-gyroscope for use on a moving craft, the combination with acompass gyroscope pivoted on supporting axes for threedegrees of freedomand movably mountportional to functions of the course, speed andlatitude of the craft, a ring mounted in said and latitude of the craft,a ring mounted for.

angular movement about said vertical axis, means for moving said ringabout its vertical axis in accordance with the angular movement of saidgyroscope about its vertical axis, and precessioninducing means adaptedto interconnect the rin and the lug for maintaining the spin axis of thegyroscope in a meridianaldirection, including a plurality of yieldablemembers mounted on the ring and disposed adjacent and above and belowsaid lug and in cooperative relation therewith, the reaction of some ofsaid members caused by the angular movement of the gyroscope about saidhorizontal axis relative to the members on departure of the spin axis ofthe gyroscope from the meridian due to the rotation of the earth beingadapted to induce and apply small precessing forces to the gyroscope forsmall departures from the meridian to return the spin axis to themeridian and to correct the tendency of the gyroscope .to wander whensubstantially on the meridian, and other of said members being adaptedto induce and apply larger precessing. forces to the gyroscope to returnthe spin axis to the meridian for larger departures from the meridian.

5. In a gyroscopic compass for use on a mov-.

-ing craft the combination of a stabilizing gyrovertical adapted tomaintain a horizontal plane, a universally mounted frame having areference plane, power driven follow-up means controlled by saidgyro-vertical for driving said frame in accordance with the position ofthe gyro-vertical to maintain said reference plane horizontaha compassgyroscope mounted on said frame, said gyroscope'having horizontaland'vertical supporting axes parallel and perpendicular to saidreference plane respectively, means reacting on said frame to apply atorque to the gyroscope about its horizontal supporting axisproportional tovertical angular displacements of the spin axis.

of the gyroscope from parallelism with the reference plane, and means.to. apply a second torque to the gyroscope about its horizontalsupporting axis proportional to functions of the course, speed andlatitude of the craft.

' 6. In a gyroscopic compass for use on a moving a craft the combinationof a stabilizing gyro-vertical adapted to maintain a horizontal plane, a

universally mounted frame having a reference plane, power drivenfollow-up means controlled byv said gyro-vertical for driving said framein accordance with the position of the gyro-vertical tomaintain saidreference plane horizontal, a compass gyroscope mounted on said frame,said gyroscope having horizontal and vertical supiporting axes paralleland perpendicular to said reference plane respectively, means reactingon said frame to apply a torque to the gyroscope about its horizontalsupporting axis proportional to vertical angular displacements of thespin axis of the gyroscope from parallelism with the reference plane,and means to apply a torque to the gyroscope about its verticalsupporting axis proportional to functions of the course and speed of thecraft.

ELLIOTT P. ROSS.

